The present invention relates to a catalyst component for polymerization of olefins. More particularly, it relates to a catalyst component which is especially useful for producing ethylene (co)polymers efficiently.
Heretofore, there have been proposed several catalyst components which are used for homopolymerization of ethylene or for copolymerization of ethylene and an alpha-olefin. Such catalyst components are prepared by contacting a base material of magnesium compound and titanium compound with a variety of compounds. In our copending application Ser. No. 418,500 filed Sept. 15, 1982, and now Patent No. 4,485,186, we disclose and claim a catalyst component for polymerization of olefins which is prepared by contacting a magnesium alkoxide, a halogenated hydrocarbon, and a titanium compound with one another. When used for polymerization of olefins, this catalyst component exhibits high catalytic activity and produces a good effect of molecular weight modification by hydrogen which works as a molecular weight modifier. In addition, it provides polymers having a high bulk density. However, in the production of polymers having a high melt index, say, higher than 30, particularly higher than 100, there is formed an undesirable amount of low-molecular fraction which is soluble in the polymerization solvent employed.